Plant Classification : Monocots vs Dicots

 

Araucariaceae

 

The Four Tribes of Malvoideae

Subfamily Malvoideae now comprises the traditional Malvaceae and has consistently emerged as a very homogeneous, monophyletic group. In a recent treatment of Malvoideae, Bayer and Kutbitzki (2003) divide the subfamily into four tribes: Gossypieae, Hibisceae, Kydieae, and Malveae.

The Malvoideae can be further ranked into the tribes listed below:

Malvoideae Tribes

Tribe Gossypieae

Tribe Gossypieae has been redifined to include eight genera: Gossypium, Cephalohibiscus, Cienfuegosia, Hampea, Kokia, Gossypioides, Lebronnecia and Thespesia. It is specifically separated from the Hibisceae tribe based on embryo structure and the presence of pigment glands. These glands are associated with the capacity to synthesize the pigment gossypol. The Gossypieae appear to be unique in possessing these glands and this capacity.

More than 50 species of Gossypium are distributed in arid to semi-arid regions of the tropics and subtropics. Of these, four species were independently domesticated for their fiber (cotton) in Africa, Asia and the Americas. Gossypium species exhibit extraordinary morphological variation, with a diverse array of characteristics, ranging from trailing herbaceous perennials to 15m tall trees.

Tribe Hibisceae

Tribe Hibisceae is best known for its largest genus, Hibiscus — one of the world's most popular horticultural plant genera — which includes more than 300 species worldwide. The tribe Hibisceae includes (but is not limited to) :  Abelmoschus, Hibiscadelphus, Hibiscus, Kosteletzkya, Malvaviscus, Pavonia, Radyera, Talipariti and Wercklea.

Tribe Kydieae

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Tribe Malveae

Tribe Malveae includes approximately 70 genera (1000 species) that encompass the majority of the morphological and taxonomic diversity in the Malvoideae subfamily. The genera of Malveae exhibit a broad geographic distribution, with representatives in both tropic and temperate areas in a variety of habitats. Around 15 of the 70 Malveae genera have mostly temperate distributions, while some of the largest genera in the tribe (Abutilon, Sida, Nototriche) have primarily tropical distributions.

The Nine Subfamilies of Malvaceae

The Malvaceae family presents many challenges for taxonomists. Opinions often differ as where to draw the lines between species, between genera, between tribes and between the subfamilies. This is not surprising — the Malvaceae family encompasses over 200 genera with close to 2,300 species!

In terms of number of species, the largest genera include Hibiscus (~300 species), Sterculia (~250 species), Dombeya (~225 species), Pavonia (~200 species) and Sida (~200 species).

In recent years an expanded circumscription of the Malvaceae family has been created, which is composed of nine subfamilies. The relationships between these subfamilies are still obscure, and the subject of ongoing discussion. The traditional Malvaceae have been moved to Malvoideae, the subfamily that now approximately corresponds to that group.

The Nine Subfamilies of Malavacae

1. Bombacoideae (formerly Bombacaceae, in part), 12 genera, (~120 species).

2. Brownlowioideae,  8 genera, (~70 species).

3. Byttnerioideae, 26 genera, (~650 species).

4. Dombeyoideae, ~20 genera, (~380 species).

5. Grewioideae, 25 genera, (~770 species).

6. Helicteroideae, 8 to 12 genera, 10 to 90 species.

7. Sterculioideae, (formerly Sterculiaceae, in part), 12 genera, (~430 species).

8. Tilioideae, (formerly Tiliaceae, in part) 3 genera, (~50 species).

9. Malvoideae, (formerly Malvaceae), 78 genera, (~1,600 species). 

Basic About Leaves : Classification

Leaves are borne on a stem in a definite fixed order, or phyllotaxy, according to species . For identification purposes, leaves are classified according to type and shape, and types of margins , tips and bases , and venation . 

Leaf arrangement. (a) Helical (top view). (b) Helical with elongated internodes (alternate). (c) Opposite (decussate). (d) Whorled (verticillate).

Leaf types. (a) Simple. (b) Trifoliate. (c) Palmately compound. (d) Odd-pinnately compound. (e) Even-pinnately compound. (f) Decompound.

Leaf shapes. (a) Linear. (b) Lanceolate. (c) Oblanceolate. (d) Spatulate. (e) Ovate. (f) Obovate. (g) Elliptic. (h) Oblong. (i) Deltoid. (j) Reniform. (k) Orbicular. (l) Peltate. (m) Perfoliate. (n) Connate.

Leaf margins of various types. (a) Entire. (b) Serrate. (c) Serrulate. (d) Dentate. (e) Denticulate. (f) Crenate. (g) Undulate. (h) Incised. (i) Pinnatifid. (j) Dissected. (k) Lobed. (l) Cleft. (m) Parted.

Leaf tips and bases. (a) Acuminate. (b) Acute. (c) Obtuse. (d) Truncate. (e) Emarginate. (f) Mucronate. (g) Cuspidate. (h) Cuneate. (i) Oblique. (j) Cordate. (k) Auriculate. (l) Sagittate. (m) Hastate. (n) Clasping.

Leaf venation. (a) Dichotomous. (b) Pinnate reticulate. (c) Palmate reticulate. (d) Parallel (expanded leaf). (e) Parallel (linear leaf).

http://www.answers.com/topic/leaf

Plant Classification : Angiosperms

Plant Classification : A Brief Introduction

Plant Taxonomy - Kingdoms and Domains

1. Carl Linnaeus in his book Systema Naturae published in 1735, classified 4,400 species of animals and 7,700 species of plants.

Linnaeus's prime contribution to taxonomy was to establish conventions for the naming of living organisms that became universally accepted in the scientific world—the work of Linnaeus represents the starting point of binomial nomenclature.

2. The formal taxonomic category Protoctista was first proposed in the early 1860's John Hogg, who argued that the protists should include what he saw as primitive unicellular forms of both plants and animals. He defined the Protoctista as a "fourth kingdom of nature", in addition to the then-traditional kingdoms of plants, animals and minerals.

The kingdom of minerals was later removed from taxonomy by Ernst Haeckel, leaving plants, animals, and the protists as a “kingdom of primitive forms.

3. Edouard Chatton (1883 — 1947), was a French biologist who first distinguished between the eukaryotic and prokaryotic systems of cellular organisation, and coined the terms themselves in his 1925 paper, Pansporella perplex: Reflections on the Biology and Phylogeny of the Protozoa.

4. Herbert Faulkner Copeland (1902-1968) , an American biologist who contributed to the theory of biological kingdoms.  He was responsible for the fourth kingdom, Monera.

5. In 1968, R. H. Whittaker proposed an additional kingdom for the Fungi.

6. Carl Richard Woese, an American microbiologist who defined the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese and which is now standard practice.

7. Carl Richard Woese, in 1990,  redrew the taxonomic tree, divided life into 23 main divisions, all incorporated within three domains: Bacteria, Archaea, and Eucarya.

1	2	3	4	5	6	7
Linnaeus	Haeckel	Chatton	Copeland	Whittaker	Woese et al.	Woese et al.
1735	1866	1937	1956	1969	1977	1990
2 kingdoms	3 kingdoms	2 empires	4 kingdoms	5 kingdoms	6 kingdoms	3 domains
(not treated)	Protista	Prokaryota	Monera	Monera	Eubacteria	Bacteria
					Archaebacteria	Archaea
		Eukaryota	Protista	Protista	Protista	Eukarya
Vegetabilia	Plantae			Fungi	Fungi
			Plantae	Plantae	Plantae
Animalia	Animalia		Animalia	Animalia	Animalia

Plant Taxonomy - Ranks

			Magnorder
Domain/ Superkingdom	Superphylum/ Superdivision	Superclass	Superorder	Superfamily			Superspecies
Kingdom	Phylum/Division	Class	Order	Family	Tribe	Genus	Species
Subkingdom	Subphylum	Subclass	Suborder	Subfamily	Subtribe	Subgenus	Subspecies
Infrakingdom/ Branch	Infraphylum	Infraclass	Infraorder		Alliance		Infraspecies
	Microphylum	Parvclass	Parvorder

source : Wikipedia